Thianaphthylmercaptothiazoles



Patented Sept. 9, 1952 THIANAPHTHYLMERCAPTOTHIAZOLES William S. Emerson and Tracy M. Patrick, Jr., Dayton, Ohio, assignors to Monsanto Chemical Company, St. Louis, Mo., a corporation of Dela ware No Drawing. Application November 21, 1950, Serial No. 196,953

agent R i l itl l l QRLR' E s/U gg in which R and R are selected from the class consisting of hydrogen, chlorine, bromine and alkyl radicals of from 1 to 4 carbon atoms.

As disclosed in our copending application Serial No. 196,951, filed of even date, the thianaphthylthiazolyl disulfides are readily prepared by contacting a 3-halomethylthianaphthene compound with ammonium dithiocarbamate. Some of the thianaphthylmercaptothiazole also is obtained in this reaction. As examples of thianaphthylthiazolyl disulfides which may be reduced by the present process to yield thianaphthylinercaptothiazoles may be mentioned 4-(3-thianaphthyl)-2-thiazolyl disulfide to yield 4-(3-thianaphthyl) -2-mercaptothiazole; 4- (5 -methyl-3 thianaphthyl) -2-thiaz0lyl disulfide to yield 4-(5- 16 Claims. (Cl. 260-4502) methyl-3'-thianaphthyl) -2-mercaptothiazo1e'; 4--

Treatment of the thianaphthylthiazolyl disulfides with a strong reducing agent yields the thianaphthylmercaptothiazoles in essentially quantitative yields. As reducing agents there may be employed dispersions of finely divided heavy metals in acids 8. g., zinc, iron or tin dust in aqueous hydrochloric acid, aqueous sulfuricacid or glacial acetic acid; easily oxidizable salts such as sodium sulfite, sodium nitrite, sodium hypophosphite, or ferrous sulfate; catalytic hydrogenation, for example, in the presence of palladium black, etc. The disulfide is contacted with the reducing agent at ordinary or increased temperature depending upon the nature of the reducing agent until formation of the thianaphthylmercaptothiazole. When working with the metal-acid systems, generally no extraneous solvent or diluent need be employed. Solvents or diluents useful in the catalytic hydrogenation of the disulfide for the production of the thianaphthylmercaptothiazoles include inert, non-reactive media such as benzene, toluene, xylene, hexane, methanol, ethanoljethyl ether, 1,4-dioxane, etc. i

The present thianaphthyl mercaptothiaz'oles are advantageously employed as rubber vulcanization accelerators. Incorporation of the present compounds into natural or synthetierubberresults in very good cures Within comparatively short periods of time. Dispersion of the thianaphthylthiazole mercaptan compounds inrulbber stocks is easily effected.

The invention is further illustrated, but not limited, by the following examples:

EXAMPLE 1 4 (3 -thianaphthyl -2 -mercaptothiazole.-- Excess powdered zinc was added to a solution of 6 g. of 4-(3-thianaphthyl) -2-thiazoly1 disulfide in 200 cc. of glacial acetic acid. After boiling for one hour, the solution was filtered hot and the funnel was washed with boiling acetic acid. The filtrate was diluted to 1 liter with water containing 25cc. of concentrated hydrochloric acid. The precipitate was separated by filtration, Washed four times with water and crystallized from a mixture of ethanol and benzene. The essentially quantitative yield of 4-(3'-thianaphthy1) 2-mercap tothiazole was collected in two crops: I, 5jg., M. P. 221-223" and II, 1 g., M. P. 220-222.-

Anal. Calcd. for C11H7NS32 C, 53.0; H, 2,81. Found: C, 52.9; H, 2.82. I

Other heavy metal-acid reducing systems or other reducing agents, e. g., hydrogen in th 'presence of palladium as catalyst maybe similarly employed to reduce the thianaphthylthiazolyl dig sulfides to the thianaphthylmercaptothiazoles.

pounds.

3 EXAMPLE 2 The accelerating efiect of the 4-(3'-thianaphthyl) -2-mercaptothiazole on the vulcanization of rubber was tested by compounding a rubber stock as follows Parts by weight Smoked sheet rubber 100,, Zinc oxide e 5 Sulfur .3 4-(3'-thianaphthyl)-2-mercaptothiazole l The compounded stock was vulcanized in the usual manner at a temperature of 126 C. The

physical properties of the cured products are set;

Other thianaphthylmercaptothiazoles may be similarly employed for accelerating the vulcanization of rubbers. Particularly suitable for this purpose are compounds having the general formula:

n, v in which is selected from the class consistin of hydrogen and alkyl radicals of from 1 to 4 carbon atoms. The, present thianaphthylmercaptothiazoles accelerate the vulcanization of rubbers, generally,

i. e., natural and synthetic rubber. The synthetierubbers with which the present compounds may be employed include rubbers such as those obtained by polymerizing a 1,3-butadiene, compound either alone or in admixture with other polymerizable compounds which. are capable of copolymerizing with the 1,3-butadiene com- Examples of 1,3-butadiene compounds which yield synthetic rubbers by polymerization or"copolymerization are 1,3-butadiene, chloroprene, piperylene, 2,3-dimethyl-1,3-butadiene, etc.- As illustrative of compounds capable of copolymerizing with such 1,3-butadienes are compounds which contain a CH2=C group, for example, aryl olefins such as styrene, vinylbiphenyl, and. vinylnaphthalene; acrylic or methacrylic acids and their derivatives such as acrylonitrile, methyl methacrylate, and methacrylamide; alkyl vinyl ethers such as methyl vinyl ether; alkyl vinyl ketones such as isoprcpenyl methyl ketone, aliphatic olefins such as isobutylene, etc.

While the present thianaphthylmercaptothie azoles are particularly valuable as rubber vulcanization accelerators, they are also valuable for a variety of, other industrial purposes. 'The chloroand bromo-derivatives may be advane tageously employed as biological toxicants; the unsubstituted thianaphthylmercaptothiazole and chlorine e d/ a y derivatives ma beus 4 as intermediates for the production of pharmaceuticals.

What we claim is: l. Thianaphthylmercaptothiazoles having the general formula in which R and R are selected from the class consisting of hydrogen, chlorine, bromine and alkyl radicals of from 1 to 4 carbon atoms.

2. .4- (3'-thianaphthyl) -2-mercaptothiazole.

3. 4.-(5-, methyl-3'-thianaphthyl) -2-mercaptothiazole.

4. 4-(6-methyl-3' -thianaphthy1) -2-mercaptothiazole. I

5. 4 (4-bromo-3'ethianaphthyl) -2-mercaptothiazole.

6. 4- (5-chloro-6'-'methyl-3-thianaphthyl) -2- mercaptothiazole.

7. The method which comprises contactin with a reducing agent a thianaphthylthiazolyl disulfide having the general formula inwhich R" and" R'- are selected from the class consisting of hydrogen, chlorine, bromine and alkyl radicals oi from 1 to 4 carbon atoms and recovering from the reaction product thianaphthylmercaptothiazoles having the general for- I! Pi ll RY \f/ /A in which R and. R are. selected from the class consisting of hydrogen, chlorine, bromine and alkyl radicals of from 1 to 4 carbon atoms and recovering: from the reaction product thianaphthlymercaptothiazoles having the general formula l inwhichR-and R? are selected from the class consisting of hydrogen, chlorine, bromine and alkylradicals'of fromlto-4 carb-onatoms.

9. The method which comprises; contacting a with a zinc-acid reducing system a thianaphthylthiazolyl disulflde having the general formula in which R and R are selected from the class consisting of hydrogen, chlorine, bromine and alkyl radicals of from 1 to 4 carbon atoms and recovering from the reaction product thianaphthylmercaptothiazoles having the general for- Ya s in which R and R are selected from the class consisting of hydrogen, chlorine, bromine and alkyl radicals of from 1 to 4 carbon atoms and recovering from the reaction product thianaphthylmercaptothiazoles having the general for-- mula in which It and R are selected from the class consisting of hydrogen, chlorine, bromine and alkyl radicals of from 1 to 4 carbon atoms.

11. The method which comprises contacting 4-(3-thianaphthyl) -2-thiaz01yl disulfide with a reducing agent and recovering 4-(3-thi-anaphthyl) -2-mercaptothiazole from the resulting reaction product.

12. The method which comprises contacting 4-(3'-thianaphthyl)-2-thiazolyl disulfide with zinc in acetic acid and recovering 4 (3'-thianaphthyl) -2-mercaptothiazole from the resulting reaction product.

13. The method which comprises contacting 4-(5'-methyl-3-thianaphthyl) 2 thiazolyl disulflde with a reducing agent and recovering 4- (5'-methyl-3-thianaphthyl) -2-mercaptothiazole from the resulting reaction product.

'14. The method which comprises contacting 4-(6-methyl-3'-thianaphthyl) 2 thiazolyl disulfide with a reducing agent and recovering 4- (6'-methyl-3'-thianaphthyl) -2 -mercaptothiazole from the resulting reaction product.

15. The method which comprises contacting 4- (4'-bromo-3-thianaphthyl) -2-thiazoly1 disulfide with a reducing agent and recovering 4-01- bromo 3' thianaphthyl) 2 mercaptothiazole from the resulting reaction product.

16. The method which comprises contacting 4-(5'-chloro-6-methyl-3-thianaphthyl) 2 thiazolyl disulflde with a reducing agent and recovering 4-(5'-chloro -6'- methyl -3'- thianaphthyl) -2-mercaptothiazole from the resulting reaction product.

WILLIAM S. EMERSON. TRACY M. PATRICK, Js.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2.196.607 Mathes Apr. 9, i940 

1. THIANAPHTHYLMERCAPTOTHIAZOLES HAVING THE GENERAL FORMULA 